The GOP's narrow but united majority made House approval of the near-$2 trillion spending plan virtually certain, despite near unanimous Democratic opposition. Passage in the evenly divided Senate also seemed assured as White House officials and GOP Senate aides said they believed they would get a crucial handful of votes from Senate Democratic moderates.

"I think that's correct," Sen. John Breaux, D-La., a leader of those moderates, said of the GOP predictions.

The budget calls for a $1.35 trillion, 11-year tax cut and 4 percent growth  half of this year's increase  for many federal programs. Bush had long sought a 10-year, $1.6 trillion tax reduction, but accepted the smaller package as the price for ensuring support from moderate Senate Democrats.

The Senate planned to debate the measure Wednesday, and final passage there seemed likely on Thursday. That would be nine days after Republicans, Bush and centrist Democrats announced they had reached an agreement, with days of further negotiations needed to complete the last details.

"I believe we do," said Senate Majority Leader Trent Lott, R-Miss., when asked if Republicans finally had the decisive votes in hand. "I haven't got a final count yet because we're growing the vote."

Bush celebrated his expected victory Tuesday evening in remarks to business executives of the Electronic Industries Alliance.

"I want to thank both Republicans and Democrats for setting out a budget that understands the projected surplus is not the government's money," he said.

The budget sets tax and spending guidelines that lawmakers are supposed to follow  but often ignore  when writing later bills that finance federal programs and change tax law. It does not need the president's signature.

But under congressional rules, budget passage would ensure that the tax cut the measure envisions could not be killed by a Senate filibuster  delays that would require 60 votes to end. The budget vote is also an important signal of where congressional sentiment lies on a president's fiscal proposals.

A House vote last week was postponed after aides realized two pages of the two-inch thick measure had been omitted.

Some Democrats insisted the final Senate vote would be close. But speaking on condition of anonymity, White House and Senate GOP aides said they expected to get more than enough votes to prevail in the Senate by winning support from some of the chamber's moderate Democrats.

Even some Democrats expressed doubts.

"I'm in the middle of the road getting run over by trucks on both sides," said Breaux, a leader of the 14 centrist Democrats and two moderate Republicans who proved pivotal to Bush's quest for a big tax reduction.

Any Republican strategy that successfully splits the Senate moderates would underline the fragility of the centrists' coalition and decrease their clout, while increasing the power of both Bush and Senate GOP leaders.

Breaux's group all voted for an earlier Senate version of the budget that had a slightly smaller tax cut. One other Democrat  Sen. Zell Miller of Georgia  has already said he will vote for the GOP fiscal plan.

Republicans said they nailed down the moderate Democratic support they needed by agreeing that the Senate's forthcoming tax bill would limit a $100 billion portion of the tax cut aimed at stimulating the economy to 2001 and 2002.

The House tax bill could spread the money over the next 11 years. House-Senate bargainers would have to find a compromise later.

In addition, they answered Democrats' insistence for an extra $6 billion for schools by crafting nonbinding language saying that providing additional money for education would be a high priority.